1. Field of the Invention
The invention relates to a substrate processing apparatus for performing processing such as cleaning of various types of substrates such as semiconductor wafers, glass substrates for photo mask, glass substrates for liquid crystal display, glass substrates for plasma display and optical disk substrates by supplying a processing liquid to these substrates.
2. Description of the Relates Art
In the manufacturing process for semi conductor devices, coating of a thin metallic film such as a thin copper film is often performed on the entire top surface and edge surface (and bottom surface in some cases) of a substrate. Then, the metallic thin film is removed by etching from the portions where coating is not required. For example, when the copper thin film is used for the purpose of facilitating for wiring, the coating of copper thin film is needed only in device seating areas. Therefore, the copper thin film portions that are adhered to the rim of the top surface, bottom surface and outer edge will not be needed. Moreover, when the substrate is transported by a substrate-transporting robot that is installed in a substrate processing apparatus, the copper may adhere to contaminate the hands of the robot. When the contaminated hands come in contact with other substrates, the copper and other unwanted substances will consequently be transferred to these substrates.
For the same reasons, the processing is performed for the purpose of removing the metallic contaminant, by thinly etching a non-metallic film such as an oxidized film, a nitride film or the like that is formed on the rim of the substrate. An apparatus, which is described in the Japanese Publication of Unexamined Application 2004-6672, performs processing of the rim portion and edge surface of the substrate through selective etching. This apparatus comprises: a spin chuck that rotates the substrate while keeping it horizontal; a blocker plate that is located above the spin chuck to control the space on the top surface of the substrate; and a nozzle that supplies the processing liquid such as an etching liquid to the bottom surface of the substrate. With this apparatus, the processing liquid that is supplied to the bottom surface of the substrate flows outward from the center to the rim portion of the bottom surface of the substrate, due to the presence of centrifugal force. Then, the processing liquid flows over edge surface to reach the top rim portion. The blocker plate is disposed in adjacent to the top surface of the substrate and the inert gas such as nitrogen gas or the like is supplied to the space between the blocker plate and the substrate. By controlling the flow rate of the inert gas, the rotating speed of substrate and the supplying quantity of processing liquid at the optimum levels, the etching of the top rim portion of the substrate is selectively performed at a pre-determined width. After the unwanted substance on the top rim portion of the substrate is removed by etching, the top and bottom surfaces of the substrate are rinsed with pure water or DIW (de-ionized water). Subsequent to the rinsing process, the spin chuck is activated to spin at high speed to spin-dry the top and bottom surfaces of the substrate.